1. Technical Field
The present invention relates to a gap adjustment apparatus. In addition, the present invention further relates to an image formation apparatus such as an ink-jet printer, though not limited thereto, that is provided with a gap adjustment apparatus.
2. Related Art
An ink-jet printer is known as an example of an image formation apparatus that ejects ink drops (fluid, including liquid) onto a sheet of recording paper such as printing paper. An ink-jet printer ejects ink drops from a recording head that is provided on the bottom of a carriage thereof. A combination of a carriage and a recording head, though not necessarily limited thereto, constitutes a non-limiting example of a “recording section” according to the invention. Recording paper constitutes a non-limiting example of a “recording target medium” according to the invention. In the following description, an ink-jet printer is simply referred to as a “printer”. A printer having the above-explained basic function is provided with a guide axis that supports a carriage while guiding the movement of the carriage in a main-scan direction. Having such a guide axis, the printer ejects ink drops from a recording head onto a sheet of recording paper that is fed on a platen while reciprocating the carriage along the guide axis in the main-scan direction, thereby performing printing thereon.
When such a printer performs printing, various kinds of recording paper that has thicknesses different from one to another depending on its particular use can be used as the target of printing. In addition, such a printer ejects ink drops onto the surface of recording paper from a recording head while moving the relative positions of the recording head and the recording paper. Therefore, at each time when the thickness of recording paper that is used as the target of printing changes from one to another, the distance between the recording head and the surface of recording paper changes accordingly. This might cause some displacement in the landing positions of ink drops, resulting in a decrease in printing precision. In an effort to provide a technical solution to such a problem, a printer having a gap controlling means (which corresponds to “gap adjustment apparatus” according to the invention) has been proposed so far, an example of which is described in JP-A-2007-1071. The printer having the gap controlling means described in JP-A-2007-1071 moves up or down a carriage (recording section) in accordance with the thickness of recording paper (recording target medium) so as to adjust the gap between the recording head and the recording paper into an appropriate distance.
In the configuration of the printer having the gap controlling means described in JP-A-2007-1071, a gap control cam (which corresponds to “cam” according to the invention) is attached to each axial end of a carriage guide axis (which corresponds to “guide axis” according to the invention). In addition, a fixation pin that functions as a cam follower is fixed to a position adjacent to the attachment position of the gap control cams. The printer having the gap controlling means described in JP-A-2007-1071 adjusts the gap between the recording head and the recording paper into an appropriate distance as follows. As the carriage guide axis turns, the gap control cams rotate. As the gap control cams rotate, the axial center of the carriage guide axis moves in a vertical direction due to camming action. In this way, the printer having the gap controlling means described in JP-A-2007-1071 controls the gap between the recording head and the recording paper into an appropriate distance.
When adjusting the gap between the recording head and the recording paper into an appropriate distance, the printer having the gap controlling means described in JP-A-2007-1071 rotates the carriage guide axis by utilizing a driving force of a paper-feed (hereafter abbreviated as “PF”) motor, which is provided in order to transport a sheet of recording paper. The PF-motor-driven rotation of the carriage guide axis for gap control places an excessive burden (i.e., load) on the PF motor when it feeds a sheet of recording paper. For this reason, if the configuration of the printer having the gap controlling means described in JP-A-2007-1071 is adopted, there is an adverse possibility that recording paper may not be transported in a smooth movement.